Multiple Object Properties JavaScript -


got code snippet in javascript defines multiple properties object.

var book = {};  object.defineproperties(book , {     _year: {         value: 2004     },      edition: {         value: 1     },      year: {         get: function() {             return this._year;         },          set: function(newvalue) {             if (newvalue > 2004) {                 this._year = newvalue;                 this.edition += newvalue - 2004;             }         }     } });  book.year = 2005; alert(book.edition);

so book has code claims alert(book.edition);would display 2.instead , displays 1. seems never executes part of accessors property code (year: get: set:). knows why happening?

edition has been defined non-writable property -- writable descriptor property hasn't been specified , false default. hence this.edition += ... fails silently. same applies _year property well.

_year: {     writable: true,     value: 2004 }, edition: {     writable: true,     value: 1 },

fiddle

note: assigning non-writable property throws error in strict mode, can add 'use strict'; pragma spot these errors more easily.

reference:


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